Simply replace the unfilled areas such as "" and "[date]" with your information.
After many years of my career with, [name of organization] it has come time to leave this organization to move into a new era of my life. Effective [date], I want to take this opportunity to thank [name of organization] for the opportunity I was given to work for this great company.
I feel very fortunate to have been part of this leading team with such fine individuals. My experience with [name of organization] has been a most pleasurable one. I will always look back on it fondly. I don't know of any other kind of organization that can compare to the way this one treats its people, customers and partners.
May [name of organization's] success continue to grow for many years to come. My best wishes to each and every one of you!